The present invention is directed to methods and compositions intended to ameliorate conditions in a circulating water system by treating such water systems to prevent problems caused by bacteria and/or cell membrane fragments from dead bacteria.
More particularly, the present invention relates to compositions containing chlorine and/or bromine in combination with chlorine dioxide that are synergistic against non-tuberculosis mycobacteria such as Mycobacterium chelonae. In addition, the present invention relates to a composition and method for removing hydrophobic or amphipathic materials that can be released into the air via aerosols during or after routine sanitization processes. Turbulent regulated waters such as waters found in spas, hot tubs, jetted bath tubs, decorative fountains and swimming pools with spray features can produce aerosols. On occasion, these waters may contain viable Nontuberculosis Mycobacteria (NTM) and/or cell membrane fragments from dead bacteria. Inhalation of aerosols containing NTM, such as Mycobacterium chelonae, or cell membrane fragments from gram-negative bacteria can result in chronic pulmonary discomfort. Therefore, one aspect of this invention relates to a method to kill M. chelonae using chlorine dioxide. Another aspect of the invention relates to physically removing viable NTM and bacterial fragments onto a surface or surfaces with high affinities for hydrophobic or amphipathic substances. A further aspect of the invention pertains to synergistic combinations of halogen oxidizers and chlorine dioxide that are efficacious against nontuberculosis mycobacteria. A still further aspect of the instant invention relates to compositions and methods for killing NTM such as M. chelonae while also physically removing dead and/or living bacteria or cell fragments with the aid of materials that are capable of binding to molecules that are essentially or partially hydrophobic.
Regulated waters are those natural and man made bodies that are used for industrial, recreational and or decorative purposes, and which can be treated with chemicals such as biocides, halogen and non-halogen shock treatments, slimicides, corrosion inhibitors, pH adjusting compounds, chelating agents and stain removers. While it is generally accepted that regulated waters such as swimming pools, metal cutting fluids, hot tubs, spas, jetted tubs and fountains contain fewer microorganisms than non-regulated waters such as lakes, streams and rivers, certain microbes are inherently tolerant to or can become resistant to certain biocides. Under these circumstances, the tolerant/resistant organisms can proliferate in such regulated water systems and can cause disease, dermal irritation or allergic reactions.
Mycobacteria of the mycobacterium tuberculosis complex are responsible for tuberculosis. Mycobacteria other than M. leprae (etiologic agent for leprosy) are referred to as nontuberculosis mycobacteria (NTM). NTM are ubiquitous in the environment and most species are either not pathogenic for humans or are rarely associated with disease. However, M chelonae is one member of NTM group that is potentially pathogenic.
Mycobacteria have a waxy coating consisting of mycolic acid, which has the general structure R1—CH(OH)—CH(R2)—COOH with R1 and R2 consisting of fatty acid chain 50-56 and 22-26 carbon atoms, respectively. The hydrophobic mycolic acid coating confers a high degree of tolerance to traditional biocides such as chlorine. Some researchers have reported that mycobacteria such as M. chelonae exist in hot tubs as a “floating slime layer” that can become airborne when the aeration jets are operating.
While treating water with biocides is an effective means of controlling the proliferation of most microorganisms, the treatment process itself can rupture the outer bacterial cell membranes of gram-negative bacteria such as E. coli. The resulting bacterial cell membrane fragments are called endotoxins As is the case with NTM, turbulent regulated waters, such as but not limited to spas and hot tubs, can produce aerosols that may contain endotoxins that can be inhaled by persons in proximity to said waters. NTM such as M. chelonae and endotoxins have been implicated as the causative agents of a pulmonary condition known generally as Hypersensitivity Pneumonitis or Granulomatous pneumonitis.
It is known in the art to use chemicals to treat regulated waters with a variety of products in order to perform functions, such as, but not limited to, sanitation, clarification, slime removal, aiding filtration, biofouling prevention and retarding scale and corrosion formation. It is also known in the art to use chlorine dioxide in the treatment of these regulated waters. For instance, Brown (U.S. Pat. No. 5,779,914) demonstrated that chlorine dioxide was capable of destroying biofilms in waters containing polyhexamethylene biguanide. Rafter disclosed methods for purifying water by adding oxides of chlorine to water, such as chlorine dioxide, in combination with metal ions (U.S. Pat. No. 5,858,246). Denkewicz also disclosed the use of silver and alumina in combination with chlorine dioxide as self-regulating compositions and methods to purify water in U.S. Pat. No. 6,254,894. In U.S. Pat. No. 6,277,288, Gargas described a water purification system that takes advantage of the synergistic benefits of using ozone and electrolytic chlorination. The electrolytic process disclosed by Gargas also can produce an oxychlorine species such as chlorine dioxide. In addition, in U.S. Pat. No. 6,551,518, Gargas disclose additional benefits of using ozonation and electrolytic chlorine generation to treat water while concomitantly generating an oxychlorine species such as chlorite, chlorine dioxide or chlorate.
The prior art fails to teach that chlorine dioxide alone, or in combination with halogens and/or in combination with substances that are capable of removing endotoxins can mitigate the reputed causative agents of hypersensitivity pneumonitis (NTM and endotoxins) in regulated waters capable of generating appreciable levels of aerosols. Moreover, while U.S. Pat. Nos. 5,858,246 and 6,254,894 show chlorine dioxide with free chlorine, these prior technologies also stipulate the need for antimicrobial effective levels of metals. The instant invention is unique in that metals are not required as co-biocides. Compositions and methods provided herein not only result in the killing of resistant organisms, but also remove dead, endotoxin-containing cell fragments.
In addition to the existing state of the art, the use of chlorine dioxide as a treatment for mycobacteria has been described in recent literature. For instance, an article published by the Centers for Disease Control and Prevention (CDC) by J. O. Falkinham entitled, “Mycobacterial Aerosols and Respiratory Disease,” states that hypersensitivity pneumonitis or granulomatous pneumonitis in swimming pool attendants was caused by mycobacteria and possibly by bacterial endotoxins (see, www.cdc.gov/ncidod/eid/vol9no7/02-0415.htm). Moreover, the same article implicated M. avium as the most likely cause of hypersensitivity pneumonitis and mycobacterial pulmonary disease hot tub users.
It is also known in the art to remove hydrophobic substances from aqueous milieu with the use of lipophilic materials. For instance, in U.S. Pat. Nos. 5,437,793, 5,698,139, 5,837,146, 6,180,010, Alper discloses compositions and methods for removing hydrocarbons from water. Similarly, Miller (U.S. Pat. No. 6,056,881) disclosed a device for removing organic substances from bilge water.